In an image forming apparatus such as a laser beam printer, an electrostatic copying machine, a plain paper facsimile machine or a printer-copier-facsimile multifunction machine, a pinch roller and a counter roller such as of a rubber are adapted to hold a paper sheet therebetween for transportation of the paper sheet. In general, the pinch roller is made of a resin which has a lower friction coefficient than the rubber.
Particularly, where the pinch roller is not disposed parallel to the counter roller but disposed at a small angle with respect to the counter roller in order to bias the held paper sheet toward one lateral side, the pinch roller is required to slip on the paper sheet after having fully biased the paper sheet to the one lateral side. Therefore, the pinch roller is required to have a lower friction coefficient
However, the pinch roller of the resin harder than the rubber is liable to damage the softer counter roller of the rubber when being brought into direct contact with the counter roller, for example, during an interval of a sheet feeding operation.
Patent Document 1 discloses that a sheet feed roller (pinch roller) unified with a shaft which rotatably supports the sheet feed roller is produced by injection-molding an elastomer composition prepared by blending resin beads with a thermoplastic urethane elastomer.
With this arrangement, the sheet feed roller is formed of the thermoplastic urethane elastomer, which is softer than the resin and has a lower friction coefficient than the rubber, whereby the sheet feed roller is moderately soft. Further, the resin beads, which function to reduce the friction coefficient, are blended with the thermoplastic urethane elastomer, whereby the friction coefficient of the sheet feed roller is reduced to some extent.